Saturday, August 21, 2010

Okay, the one without the chocolate all over their face is Ratty. He, Ratty, is 20 weeks old and weighs 360g. He is slim, active, well muscled (for a rat) and, of course, eats a very high fat diet. In fact he eats exactly the same food as we do with extra fried belly pork and cheese to snack on between meals of scrambled egg yolks (in butter), Bolognaise sauce, chilli mix or beef stew, should he ever get hungry between those main meals. My wife gave him a grape once. I removed it from his cage when it went mouldy.

I don't think he has metabolic syndrome. He eats an ad lib diet which provides about 70% of his calories from fat.

Now, I was looking through Axen and Axen's 2010 paper on managing metabolic syndrome in rats. First you have to make them obese. Hmmmm, now how might you do that? Ah ha! A high fat diet. In fact just 60% of calories will do the trick. Wow. Lets look at Table 1, column 2, HF diet used to induce obesity in rats. There it is: 60% fat, 25% protein and a mystery 15% carbohydrate.

Plus this line in the methods:

"The contents of saturated: monounsaturated: polyunsaturated fats were 25.3%:43.3%:31.3% in the HF diet and 31.7%:42.7%:25.5% in the VLC and HC diets (ω-3 fatty acids comprised ~2% of total fat)."

OK, are you thinking the carbohydrate was sucrose? Me too. Wrong! But the fat was supplied by Proctor and Gamble.

If you work through the paper to find out how this obesogenic diet was developed you get to ref 9, which is Axen and Axen again, this time in 2006. Once again, Table 1 for diet composition:

This tells us nothing more about the obesity diet (it's not really what the paper is about) but the fat was supplied by Proctor and Gamble. The paper does have another reference about the obesogenic diet, number 13 this time, which leads us to a gem from another Axen paper, just Kathleen and friends this time:

I think I have to put it here in full as it is really too important to summarise. They have a diet which develops metabolic syndrome in rats which CANNOT be prevented by restricting calories to normal body weight. Has any one heard of the "slim but metabolically obese" concept? The skinny type 2 diabetic? Kathleen Axen knows EXACTLY how to produce a skinny type 2 diabetic rat! And this is the paper. And here is the abstract:

"High fat, low carbohydrate diets are popularly advocated for weight loss and improvement in metabolic Syndrome X, a constellation of risk factors for type 2 diabetes mellitus and cardiovascular disease. The effects of an energy-restricted (to prevent weight gain in excess of normal growth) high fat (60% of energy), low carbohydrate (15%) diet were assessed in both lean rats and in rats previously rendered obese through ad libitum consumption of the same high fat diet. In obese rats, restriction of intake failed to improve impaired glucose tolerance, hyperinsulinemia, and hypertriglyceridemia, although it lowered visceral fat mass, liver lipid content and in vitro insulin hypersecretion compared with rats continuing to consume the high fat diet ad libitum. In lean rats, restricted intake of the high fat diet impaired glucose tolerance and increased visceral fat mass and liver lipid content. These findings support the conclusion that, in the absence of weight loss, a high fat, low carbohydrate diet not only may be ineffective in decreasing risk factors for cardiovascular disease and type 2 diabetes but may promote the development of disease in previously lower risk, nonobese individuals."

I think that that's pretty conclusive. A diet of 60% fat makes a rat glucose intolerant even if you starve it (and rats in the starved group will be HUNGRY, unlike Ratty) to a normal bodyweight. And no sucrose in sight. High fat and restricted carbohydrate diets might PROMOTE type two diabetes in rats (and people?) and give them heart attacks (do rats have heart attacks?) even if they were slim to begin with and stay slim on the diet. That's me and Ratty all right.

Ratty and I are doomed to diabetes it appears.

BTW, did I mention that Proctor and Gamble provided the fat?

Which fat? Well, here's the section which never made it in to the abstract:

"the other group was fed a high fat (HF;347 g fat/kg diet) low carbohydrate diet (22.6 kJ/g, 5.4 kcal/g). The HF diet was comprised of powdered Purina 5001 and hydrogenated vegetable fat (Proctor & Gamble, Cincinnati OH), with casein, L-methionine, AIN vitamin mix, and AIN mineral mix (Bio-serv, Frenchtown, NJ) (17) added to provide equivalent protein concentrations (LF, 234 g/kg diet; HF, 331 g/kg diet) and equivalent vitamin and mineral contents for the two diets. The hydrogenated vegetable fat contained 25% long-chain saturated, 44% monounsaturated and 28% PUFA, with 17% of total fat as trans fatty acids (manufacturer’s communication). This high fat, low carbohydrate diet was used because of the more pronounced obesity it has produced in rats in our laboratory than have several commercial high fat diets."

Stop, rewind, slow frame:

"with 17% of total fat as trans fatty acids"

That's a very special fat. Magic fat. Unless I am very much mistaken Proctor and Gamble make commercial bootpolish marketed as fit for human consumption. I think it's called Crisco. They have been poisoning America with it for decades.

DO NOT, UNDER ANY CIRCUMSTANCES, BASE YOUR DIET ON 60% OF CALORIES FROM FAT WHICH INCLUDES 17% TRANS FATTY ACIDS.

DO NOT DO IT.

Just say no.

But oh, oh, oh, Kathleen, why did you leave this out of the abstract????????????

People will think that eating fat makes you fat......

It certainly will if Proctor and Gamble supplied it.

Peter

OK, the 2006 and 2010 studies need looking at next in some detail. They are really quite funny in combination. Also, to give K Axen her due she does discuss trans fat toxicity extensively in the discussion of the paper. But not the abstract. There it's "fat" all the way. A pinguid diet (for Gary; ok do I win at Scrabble now?).

Actually, re reading the last sentence of the abstract: This is a very unpleasant piece of writing. Would people go as far as the full text to read what the paper is actually about?

Back comments section of the uric acid post _Flo passed on the news of the death, due to stomach cancer, of a prominent long term Optimal Diet follower. This is not the sort of in formation that should be ignored although, from an individual case, I doubt whether there is anything we will every actually find out about causation. The main thing it brings home forcefully is that none of us is immortal and a good diet will not allow us to automatically reach an advanced age. The OD and similar approaches brings marked improvement in many of the diseases of civilisation but clearly not all. For someone who has achieved remission from multiple sclerosis or ankylosing spondylitis it is depressing to accept that those same diet changes might not be cancer protective, or not completely so.

_Flo has made her own modifications to her diet which are sensible in their own right and represent her choices. As regards the type of cancer it quite interesting to note that Poland has one of the highest rates of stomach cancer in the world. This snippet was passed along by another friend on the net and is corroborated by pubmed. It does suggest that speculation based on the location/type of the tumour may not be representative a specific diet related factor, rather the result of living in Poland. Of course it might be diet related.

I have my own personal tweaks to the OD and do not see any clear way of improving what I have already achieved.

So let be set here in print. No one has all of the answers.

I thought I would take this chance to discuss the possibility that there are people for whom low carbohydrate eating might be genuinely problematic. I have picked up a couple of hints along these lines over the years, so here we go with some thoughts.

I discussed a secondary prevention trial for heart disease here. All of these people had glucose regulation problems (that's part of my definition of having a heart attack). Adding 500-600kcal of either corn or olive oil to a very low fat diet precipitated diabetes in two of these individuals. Why? That's a good question. Type two diabetes is intrinsically linked to insulin resistance. Normally people eating a bolus of fat will reduce the rest of their calorie intake to compensate. Anyone who didn't would have placed a significant carbohydrate load on top of fat induced insulin resistance (even vegetable oils induce this, although palmitic acid does a rather better job) and failed to deal with their relatively high carbohydrate intake. Pure speculation but a low fat diet, with 80ml of added vegetable oil, undoubtedly triggered 2 cases of type two diabetes. I found that interesting.

Second hint was Jenny Ruhl's comment that she had come across very, very occasional individuals with diabetes who responded to low carbohydrate eating by deterioration of glycaemic control. Again, I have no details what so ever but anyone's ears should prick up when they hear things like this. Denial is not where it's at.

Then Carb Sane introduced me to the Otsuka Long-Evans Tokushima Fatty strain (OLETF) of rats. These rats are a diabetologists dream. Under fixed isocaloric conditions they gain weight and fat mass in direct proportion to the percentage of fat in an exactly measured 28.7 joule daily ration. Like, wow. Fat really does make you fat!

Of course the OLETF rat is described as a Good Model for human type two diabetes. It explains exactly why all diabetics put on to a LC, high fat diet become obese and hyperglycaemiac. What do you mean, they don't? Oh, not enough testosterone! The OLETF rats only become diabetic if they are male. That's why all type two diabetics are blokes. What do you mean, women get type two diabetes? But out model says only blokes should. And it's a Good Model...

OK facetiousness aside, what is happening in the OLETF rats? Is it possible that there are some humans out there with OLEFT rat style type two diabetes. Well, why not?

Let's have a look at what is happening from the point of view that insulin is the primary hormone in the development of obesity. If you think about someone eating just once a day, essentially all of their calories are going to get stored. Glycogen in the liver and fat in the fat. What determines weight gain is how much of that stored energy fails to be extracted from storage before the next meal arrives.

Summary: No one stores lipids or glucose in their blood stream. It all goes in to short term storage. What comes out determines weight loss. Insulin determines what comes out.

OLETF rats, on high fat, fixed calorie diet of 28.7 joules per day put all of this energy in to storage but fail to extract as many of these calories/joules from storage as those OLETF rats on 28.7 joules of a high starch diet. What is going on?

If you accept the insulin hypothesis of weight gain, the answer is that dietary fat is being trapped in adipocytes by excessive blood insulin. There must be excess insulin.

Why is the insulin elevated when there is a reduced dietary stimulus for insulin production? These rats have peripheral, almost certainly muscle based, insulin resistance. But only on a high fat diet.

High fat diets put lipids in to muscles, muscles full of lipid don't accept glucose. If the system works correctly the muscles run on lipids until there is a balance between fat supply rejecting glucose and fat depletion allowing glucose acceptance. A few billion years is ample time to get this system working correctly to maintain normoglycaemia in the face of varied macronutrient intakes from day to day.

What might be broken in this system in the OLETF rat?

Well, if you can get lipids in to muscle cells but cannot then use that lipid for beta oxidation you would expect to develop muscle insulin resistance in proportion to the amount of fat you supply, ie if the fat enters the muscles but does not go any further those muscles will become insulin resistant and stay insulin resistant. If muscles are not accepting glucose because they are insulin resistant the glucose is going to have to be dealt with by increased levels of insulin. Hyperglycaemia is unacceptable.

The extra insulin needed to maintain normoglycaemia then traps stored dietary fat in adipocytes. The rats get fat because they cannot get fat out of adipocytes. They will also do less running around and will probably feel colder than normal rats because they have no access to their fatty tissue for energy supplies. If they had access to food they would eat more, but 28.7 joules per day was the limit in this experiment. If they had access to more calories they would clearly eat more because no one likes the hunger and shivering produced by sequestering a chunk of your caloric fat intake in your adipocytes and locking it in there with insulin.

Once your fat cells get full enough they will spill free fatty acids because they are now too full to listen to insulin any more. These FFAs join those intra cellular muscle tissue di and tri glycerides from the metabolic defect. Intra myocyte fatty acids still have no where to go, so muscle insulin resistance rockets, plasma glucose rockets and you have a superb model of fat induced obesity and peripheral insulin resistance.

Glucose enters mitochondria as pyruvate. Fatty acids enter mitochondria as acyl CoA moieties. The place to be looking for explanations for the syndrome seen in the OLETF rat is in fatty acid processing. My guess is that lipid molecules get in to myocytes but never get effectively passed to the mitochondria. Quite what testosterone has to do with this is beyond me, it's not me that is suggesting the OLETF rat is a good model for human type 2 diabetes!

You have to ask what would have happened on a ketogenic diet. Would ketosis have side stepped this problem? Ketone bodies enter mitochondria without any need for long chain fatty acid transporters. They use monocarboxylate transporters, just like pyruvate... You don't really think that Kaneko et al would so something as stupid as putting an OLETF rat on a ketogenic diet? But it would have been interesting. I'm not sure it would side step the problem but it might. I'm certainly not expecting a diabetologist to find out for me.

I really enjoyed the OLETF rat. Does it tell me something about type two diabetes? Only that there might be very, very special people who respond to dietary fat with hyperglycaemia.

I never did find any teeth in my chickens. I understand hen's teeth are rare. So are OLETF humans.

Friday, August 06, 2010

It only needs a brief glance through the literature to realise that uric acid is a prime mover in metabolic syndrome and might reasonably compete with cholesterol as the premier mammalian-synthesised molecule of self destruction.

Until of course you come across interesting papers like this one which suggests that uric acid is a signal of tissue injury, a mobiliser of repair systems and, in particular, a recruiter of endothelial progenitor cells.

In modern terms, stepping on a land-mine will produce a surge of uric acid to blunt the effects of the renal ischaemia which will occur as you bleed out through the remains of where your foot used to be. In evolutionary terms you can see how surviving acute trauma might be beneficial and it looks like uric acid is seriously useful in this context. Stepping on a land mine every day fairly rapidly becomes problematic in terms of all cause mortality and even uric acid is unlikely to maintain its efficacy with prolonged usage. Chronic drug induced hyper uricaemia appears to be a Bad Thing in that it blunts the benefits of acute elevations.

If you don't live in a heavily land-mined country you are (a) lucky and (b) more likely to be injured by a bottle of cola or a bowl of apples. Or maybe oranges, stawberries, kiwis etc. Whether it is simply the fructose in the cola or some other plant nasty in the fruit in addition to fructose isn't particularly clear. But your body produces a spike of uric acid in response. It's been injured.

It is perfectly possible to consume cola or fruit on a chronic basis without the immediately obvious effects of repeatedly treading on a land mine.

This leads me to whether there are direct benefits from minor damage of eating fruit via hormesis or whether it is just all bad. I suspect it depends on the dose and the chronicity. When you look at WHEL and PPT there may well be some sort of accommodation which leaves total mortality unchanged by eight years of eating extra fruit and veg. There seems to be little doubt that an acute rise in uric acid is beneficial and chronically elevated uric acid may be less so. This flies in the face of Kwasniewski's opinions about uric acid, the more the better. But he is talking about elevated uric acid in a LC high saturated fat situation, not after eating a bowl of apples a day for a few years.... Of course he never cites references but I'm keeping an eye out!

Ascorbate is interesting as it is a rather ubiquitous antioxidant and does appear to be used by humans for assorted essential functions, all be it in very small amounts, despite the fact we cannot synthesise it. Most mammals tightly regulate their ascorbate production to their needs as they can produce it on demand. Not so humans. We don't produce it and our intake is completely random, varying from 10mg per day or less on an all meat diet to a few 1000mgs if you fall face down in a clump of cranberries and keep eating all day.

The chances of you meeting the cranberries every day for six weeks are slim, so if you want to study the effect of relatively high doses of ascorbate on free radical mediated processes in humans you have to use supplements. Eating 1000mg represents an awful lot of berries but is a common supplement dose.

This group in Spain actually pre empted the group in Germany in demonstrating the adverse effects of ascorbate supplementation on the effects of exercise.

If you dose with 1000mg ascorbate daily you will scavenge the free radicals and blunt the increase in both muscle mass and mitochondrial number which should have been generated by those free radicals. You might expect this and it's worth noting that the effect appears to clearly detectable but far from complete.

I have worked on the assumption that taking antioxidants should down regulate your own endogenous antioxidant production. The Spanish group used rats for this part of their research and did indeed find that gene expression for synthesis of both superoxide dismutase and glutathione peroxidase are markedly down regulated. A zero increase with ascorbate supplemented exercise compared to a 3.5 fold increase after three weeks of unsupplemented exercise.

Think of the implications. You exercise, exercise generates free radicals, free radicals build muscle and upregulate production of antioxidant enzymes. So exercise is, fundamentally, antioxidant (while ever it is kept within the limits which can be accommodated by synthesis of SOD and GPx). Obviously ultra-marathon runners must be willing to injure themselves for their sport.

Mega dosing with ascorbate markedly blunts the induction of the intrinsic antioxidant system of mammals, even of a rat which naturally produces ascorbate.

What about resveratrol? Feed it to a mouse in quantities equivalent to between 150 and 1,500 bottles of wine a day and you get some improvement in inflammatory markers. Do you simultaneously down regulate SOD and GPx synthesis? Now there is a question!

That will be a cracking study. The answer will be yes if resveratrol really scavenges significant numbers free radicals. Our own endogenous antioxidant systems are fine tuned to our needs. What does a blanket treatment with a highly potent antioxidant do to our ability to respond to the daily alterations in free radicals? Free radicals carry information. How do we replace the information lost if they are stuck to a resveratrol molecule?

Luckily our bodies try hard not to absorb the stuff and normally metabolise it to sulphated or glucuronated forms within minutes. It's unlikely that we ever have much free resveratrol (or dark chocolate favanoids either, phew) in our bloodstream until human ingenuity invented the resveratrol chewing gum.

Unintended consequences anyone?

Peter

BTW The Wiki article on resveratrol appears to be very contentious. Wiki becomes a battleground once you get on to sticky subjects like cholesterol and, apparently, resveratrol. I've kept the text for when it gets edited to "Resveratrol explains the French paradox and will make us live for ever"

Many thanks to Blogblog for the link to that hysterical abstract, I just love it. If anyone thinks that resveratrol is the answer to the French Paradox, or that there even is a French Paradox, or that plants will gift us eternal youth, then you're in the wrong place on the net I'm afraid, just hit the back button!

About Me

I am Petro Dobromylskyj, always known as Peter. I'm a vet, trained at the RVC, London University. I was fortunate enough to intercalate a BSc degree in physiology in to my veterinary degree. I was even more fortunate to study under Patrick Wall at UCH, who set me on course to become a veterinary anaesthetist, mostly working on acute pain control. That led to the Certificate then Diploma in Veterinary Anaesthesia and enough publications to allow me to enter the European College of Veterinary Anaesthesia and Analgesia as a de facto founding member. Anaesthesia teaches you a lot. Basic science is combined with the occasional need to act rapidly. Wrong decisions can reward you with catastrophe in seconds. Thinking is mandatory.
I stumbled on to nutrition completely by accident. Once you have been taught to think, it's hard to stop. I think about lots of things. These are some of them.

Organisation (or lack of it)!

The "labels" function on this blog has been used to function as an index and I've tended to group similar subjects together by using labels starting with identical text. If they're numbered within a similar label, start with (1). The archive is predominantly to show the posts I've put up in the last month, if people want to keep track of recent goings on. I might change it to the previous week if I ever get to time to put up enough posts in a week to justify it. That seems to be the best I can do within the limits of this blogging software!